rut.ts

isRutLike()

Quick bounded format check to determine if a value looks like a RUT, without validating the verifier digit.

Basic Usage#

TypeScript
import { isRutLike } from 'rut.ts'
 
isRutLike('12.345.678-9') // true
isRutLike('not-a-rut') // false

Type Signature#

TypeScript
function isRutLike(rut: unknown): boolean

Parameters#

  • rut (unknown) - The value to check

Return Value#

Returns boolean:

  • true if the string looks like a RUT format
  • false otherwise

Examples#

Valid Formats#

TypeScript
import { isRutLike } from 'rut.ts'
 
// All RUT-like formats
isRutLike('12.345.678-9') // true (standard format)
isRutLike('12345678-9') // true (no dots)
isRutLike('123456789') // true (no formatting)
isRutLike('1.234.567-K') // true (7-digit body)
isRutLike('09.068.826-K') // true (leading zeros)

Invalid Formats#

TypeScript
import { isRutLike } from 'rut.ts'
 
isRutLike('abcdefgh') // false (letters)
isRutLike('') // false (empty)
isRutLike('12.34.56-7') // false (wrong dot pattern)
isRutLike('12.345678-9') // false (ambiguous dot grouping)
isRutLike('12,345,678-9') // false (commas not supported)
isRutLike(123456789) // false (not a string)

Difference from validate()#

isRutLike() only checks if the format looks correct. It does NOT validate the verifier digit. Use validate() for full validation including verifier digit check.

TypeScript
import { isRutLike, validate } from 'rut.ts'
 
const rut = '12.345.678-0' // Wrong verifier (should be 5)
 
isRutLike(rut) // true ✅ (format is correct)
validate(rut) // false ❌ (verifier is wrong)

Use Cases#

Early Form Validation#

TypeScript
import { isRutLike } from 'rut.ts'
 
function handleInput(value: string) {
  if (!isRutLike(value)) {
    showError('Please enter a valid RUT format')
    return
  }
 
  // Continue with full validation
  if (validate(value)) {
    saveRut(value)
  }
}

Filter Lists#

TypeScript
import { isRutLike } from 'rut.ts'
 
const inputs = ['12.345.678-5', 'invalid', '18.972.631-7', 'abc', '9068826K']
 
// Quick filter for RUT-like strings
const potentialRuts = inputs.filter(isRutLike)
console.log(potentialRuts)
// ['12.345.678-5', '18.972.631-7', '9068826K']

Pre-validation Check#

TypeScript
import { isRutLike, validate } from 'rut.ts'
 
function validateRut(input: unknown): boolean {
  // Quick type/format check first
  if (typeof input !== 'string' || !isRutLike(input)) {
    return false
  }
 
  // Then do full validation (more expensive)
  return validate(input)
}

Performance#

isRutLike() is faster than validate() because:

  • It checks type, length, and accepted RUT shapes first
  • It does not calculate the verifier digit
  • It rejects oversized input before running the shape checks

Use it for quick filtering before full validation.

Related Functions#

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